Cranes require vertical lifting, but crane operators cannot determine whether the hook is in the vertical position. Thus, the detection of the verticality of a crane hook becomes an important issue that must be urgently resolved, whether it is for eliminating the possibility of damaging the surrounding equipment or injuring the nearby personnel by the deflection of the weight caused by the eccentrically lifting hook or other causes, achieving automatic operation of a crane, or implementing safe hoisting and reducing crane collaborative hoisting risk. In order to reduce the risk of crane collaborative hoisting, the applicant has put forward an idea of dynamically displaying the crane collaborative hoisting risk for the collaborative operator. Currently, angle sensors are always used to detect the deviation angle of the hook wire in order to find out the verticality condition of the crane lifting pulley block or the crane hook. For one example, an angular measurement device realizes the two-dimensional detection of the crane hook wire, as is shown in FIG. 2, where two U-shaped frames, UX and UY, are set in two mutually perpendicular directions. A hook wire C with a hanging weight L runs across both frames, which are kept in touch with each other. Two angle sensors, EX and EY, are installed on the rotation shafts of U-shaped frames, UX and UY, respectively. The angle sensors output deviation signals when rotating with the rotation shafts of the U-shaped frames and when hook wire C deviates from plumb. For another example, a device for detecting the deviation angle of crane hook wire is shown in FIG. 3. A sleeve 2 is set outside of the hook wire 3, which is located in the fixed pulley end of the crane jib head 1. An angle sensor 4 is installed on the outer wall of the sleeve 2. An anti-rotating mechanism 5 restricting the rotation of the sleeve 2 is installed between the crane jib head 1 and the sleeve 2. The angle sensor 4 outputs the deviation signal by deflecting with the sleeve 2 when hook wire 3 deviates from plumb. All above mentioned devices cannot detect the hoisting vertical deviation angle of crane accurately because there is an inherent uncertain deviation in the hook wire itself.